title: Mutational status of KIT and PDGFRA and expression of PDGFRA are not associated with prognosis after curative resection of primary gastrointestinal stromal tumors (GISTs).
abstract: BACKGROUND
  The aim of this study was to investigate if immunohistochemical expression and mutational status of KIT and PDGFRA in GISTs are associated with the clinical course and disease-free survival after curative resection of the primary tumor without adjuvant systemic therapy.
  
  
  METHODS
  Paraffin-embedded tumor sections of 95 GISTs were analyzed for KIT and PDGFRA expression by immunohistochemistry. PDGFRA expression was judged using a scoring system subdividing tumors in negative/weak and strong immunoreactivity groups. For mutation analysis, exons 9, 10, 11, 13, and 17 of KIT and exons 10, 12, 14, and 18 of PDGFRA were sequenced.
  
  
  RESULTS
  Of 95 R0-resected GISTs, 69% showed strong PDGFRA immunoreactivity. Gastric GISTs revealed a significantly higher rate of strong PDGFRA immunoreactivity (P = 0.01) and longer DFS (P = 0.015) than GISTs of the small intestine. KIT mutations were detected in 43 of 63 (68.3%) completely sequenced cases while PDGFRA mutations were identified in 6 cases (10%). In multivariate analysis, neither KIT/PDGFRA expression nor mutational status of KIT or PDGFRA were independent prognostic factors. Only mitotic rate predicted recurrence independently.
  
  
  CONCLUSIONS
  Our data do not support the notion that expression of PDGFRA or mutations in KIT or PDGFRA are independent prognostic factors after curative resection of primary GIST.
authors.affiliation: Department of Visceral, Thoracic and Vascular Surgery, Technische Universität Dresden, Dresden, Germany. alexander.kern@uniklinikum-dresden.de
authors.forename: Alexander
authors.initials: A
authors.lastname: Kern
authors.forename: Heike
authors.initials: H
authors.lastname: Görgens
authors.forename: Dag-Daniel
authors.initials: DD
authors.lastname: Dittert
authors.forename: Stefan
authors.initials: S
authors.lastname: Krüger
authors.forename: Konrad Klaus
authors.initials: KK
authors.lastname: Richter
authors.forename: Hans K
authors.initials: HK
authors.lastname: Schackert
authors.forename: Hans-Detlev
authors.initials: HD
authors.lastname: Saeger
authors.forename: Gustavo
authors.initials: G
authors.lastname: Baretton
authors.forename: Steffen
authors.initials: S
authors.lastname: Pistorius
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D046152:Gastrointestinal Stromal Tumors / Q000235:genetics* / Q000378:metabolism / Q000601:surgery*; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D018331:Nevus, Spindle Cell / Q000473:pathology / Q000601:surgery; D011379:Prognosis; D011446:Prospective Studies; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics* / Q000378:metabolism*; D015996:Survival Rate; D055815:Young Adult
chemical_list: D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha